1. Technical Field
The present invention relates to a piezoelectric driving device, and various apparatuses such as a robot including a piezoelectric driving device.
2. Related Art
In the related art, a piezoelectric actuator (piezoelectric driving device) using a piezoelectric element has been known (for example, see JP-A-2004-320979). A basic configuration of this piezoelectric driving device is a configuration in which four piezoelectric elements are arranged on each of two surfaces of a reinforcing plate to have two rows and two columns, and accordingly, eight piezoelectric elements in total are provided on both sides of the reinforcing plate. Each piezoelectric element is a unit in which a piezoelectric body is interposed between two electrodes and the reinforcing plate is also used as one electrode of the piezoelectric element. A protrusion which comes into contact with a rotor, which is a body to be driven, to rotate the rotor is provided on one end of the reinforcing plate. When the AC voltage is applied to two piezoelectric elements diagonally disposed among the four piezoelectric elements, the two piezoelectric elements perform an expansion and contraction operation, and accordingly, the protrusion of the reinforcing plate performs a reciprocal operation or an elliptic operation. The rotor, which is a body to be driven, rotates in a predetermined rotation direction according to the reciprocal operation or the elliptic operation of the protrusion of the reinforcing plate. In addition, it is possible to rotate the rotor in a reverse direction, by switching the two piezoelectric elements to be targets of application of the AC voltage, with the other two piezoelectric elements.
In the related art, a so-called bulk-like piezoelectric body has been used as a piezoelectric body used in the piezoelectric driving device. In this specification, the “bulk-like piezoelectric body” means a piezoelectric body having a thickness equal to or greater than 100 μm. A reason for using the bulk-like piezoelectric body is because it is desired to increase the thickness of the piezoelectric body, in order to sufficiently increase an amount of force applied to a body to be driven from the piezoelectric driving device.
However, it is desired to miniaturize the piezoelectric driving device to be used as a miniaturized actuator which can be accommodated in a small space. However, when the thickness of the piezoelectric body is decreased for miniaturizing the piezoelectric driving device, a great driving current is necessary. As the driving current increases, a thickness of a wiring also increases, and accordingly, when the piezoelectric driving device is disposed in a small space (for example, in a joint of a robot), wiring space may be insufficient.